Work holder



Patented Nov. 14, 1939 i UNITED STATES PATENT OFFICE WORK HOLDER.

John J. Groden, Philadelphia, Pa.

Application September 1, 1938, Serial No. 227,875

11 Claims. (Cl. 175-367) This invention has to do with work holders bedded in a non-magnetic material such as an such as are commonly employed on machine app opriate l min m ll y. The face pl e is tools for the purpose of holding work that is berendered of a construction correspend t e ing operated upon. The invention is concerned arrangement of ho ses o magnets in e primarily with work holders of the magnetic type. netic assembly, the Construction including eSSeh- 5 The invention has in view, as its foremost obholly a p ura ty f p s f ma netic material jective, the provision of a magnetic work holder Such as iron or steel that are arranged to conwhich is characterized by the presence of per- Stitllte continuations Of the horseshoe magnets, manent magnets. When permanent magnets are d a e maintained in Spaced relationship y employed it is impossible to control the magnetic being em e ded n ona net e ial. 0 force by controlling an electrical current, as in Other more detailed objec s and d a ta es those cases in which the magnetic force is gen- Will in part be o pp and in P be he eerated by electrical current, Hence two iminafter stated, as the description 0f the invenportant conditions are presented which must be tion proceedsadequately accommodated in order to provide a The invention, ther Comprises a W 15 work holder that is usablc'under practical conholder characterized y t presence of p maditions. nent magnets which are included in a magnet as One of these conditions is the necessity for sembly that s movable With p t to a face making provision ior accurately truing up the plate against Which t e Work engages pp work on the holder, and this is'particularly imp ate m a m or moving the m n t as- 20 portant when the machine lool is of the rotary sembly W t pec t the face p a e u der the type, such as a lathe or grinder. Another factor principles o cal advantage is also p is that of easy removal of the w rk from th vided. The particular construction of the face holder, plate and magnet assembly is also an important With the foregoing conditions in mind the in p t of the invention. 25 vention has in view, as a further detailed object. For a full and r complete und r andin of the provision of a work holder including permae invention ence may be had to the folnent magnets together with means for diminish w g s p n a d a y ng drawin ing the effects of the magnets as occasion dewherein 3o mands, Figure 1 is a section through a work holder More in detail this invention has in view, as made in accordance With the p p Of th s '1- an object, the provision of a work holder includ- Vehtleh,

ing a face plate against which the work is Figure 2 s a perspective v w f the m et adapted to engage, and with which face plate is assembly and face plate with the latter broken associated a magnet assembly that is movable y, and 35 with respect thereto. When the magnetic as- Figure 3 is a bottom p View of the gear sembly is spaced away from the plate the magmechanism for Causing movement o the m netic force effective at the surface of the plate et assemblyis greatly diminished as compared to the condi Referring n w t t d w erein like reftion in which the magnetic assembly is in close erehce characters denote D Dd Hg parts, 40 juxtaposition to the face plate. and more particularly to Figure 2, the magnet Another somewhat more detailed obj t f th assembly is referred to in its entirety by the refinvention is the provision of means which are ee Character This magnet s y M operable under the principles of mechanical ad- Comprises a plurality of hOreShOe e s I0 vantage for moving the magnetic assembly with (see Figure 1) which are made from a ood ma- 45 respect to the face plate. Other more detailed ter al av ng permanent t c properties objects and advantages of the invention are assuch as iron. sociated with the provision of mechanism in the In Constructing the magnet assembly M t e reattainment of this objective. quired number of permanent horseshoe magnets Another important feature of the present in- '0 e placed in a mold together with a sleeve 50 vention is the actual construction of the face H (see Figure 1) which is provided with large plate and the magnet assembly. It is an object exterior screw threads, as shown at I2. A nonof this invention to provide a magnet assembly magnetic material such as an app p ate alumiin which a plurality of horseshoe magnets are num alloy is then cast about the magnets l0 and included. Thesehorseshoe magnets are eminto the interior of the sleeve ll. 55

In this connection it is noted that the sleeve H, which onstitutes the shank of the magnet assembly M, is formed with a bore II which is enlarged at l4 to define a shoulder l6. Thus with the aluminum alloy, designated I6, cast into the interior of the bore l3 of this sleeve H, the shoulder at l6 insures of strong structural efi'ects. I

The face plate of the holder is referred to in its entirety by the reference character F, and is shown as consisting of a. circular plate construction I! that is carried at the forward end of a cylindrical member l8 having a smooth inner cylindrical bore I3 complemental to the cylindrical surface 20 on the magnet assembly M.

15 This plate I! is preferably removably held in the 30 substantial alignment with the ends 23.

35 with means for permitting the same to be gripped cylindrical member l8.

The circular plate structure comprises a plurality of pieces 2| of material having good magnetic properties, such as iron, which pieces are embedded in a body structure of a non-magnetic material such as an aluminum alloy as designated at 22, and arranged to constitute substantial continuations of the horseshoe magnets It.

As shown in Figure 2, the ends of the horseshoe magnets 10 lie fiush in the face of the magnetic assembly M, as shown at 23, and when the -magnetic assembly M is in engagement with the face plate F the pieces 2| are intended to be in With the plate structure removable, the size and shape of the pieces 2| of magnetic material may be varied as occasion demands.

The cylindrical member I8 may be provided by a spanner wrench, such as the openings shown at 24. At its inner free edge this cylindrical member I8 is reduced in thickness and the exterior surface thereof provided with screw threads, as indicated at 25. v

A gear carrying member 26 is of -a cylindrical formation corresponding to the member l8 and is interiorly threaded, --as shown at 21, with the latter threads engaging the threads 25 to maintain the members I8 and 26 in assembled relationship. 7

Extending inwardly from the cylindrical wall of the carrier 26 is a horizontal flange structure 28 that constitutes an abutment for limiting movement of the magnetic assembly M in one direction, the later being adapted to engage thereagainst.

Disposed within the carrier 26 is a sleeve-like screw. member 29 having a bore at 30 which is formed with threads 3| that are complemental to the threads l2 on the sleeve II and in mesh therewith. This sleeve 29 terminates in 'an outturned flange 32 that engages the flange 28. The outer peripheral edge of the flange 3 2 is formed with a series of gear teeth defining a circular rack 33, the latter being slightly inclined, as shown in the lower part of Figure 1 so as to properly engage with the beveled gears or pinions 34.

Each of the pinions 34 is carried by a shaft 35 that has wrench engaging means in the form of a noncircular socket 36 at one end, and which shaft has bearing in an opening 31 formed in the wall of the'carrier 26. At the other side ofthe pinion 34 the shaft35 is reduced, as shown at 38, and has bearing in an opening 39 formed in a sleeve 40 that is carried by the work holder 26 and engages the screw sleeve 29.

This sleeve 4|! may be integrally formed with an end piece shown at 4| that is secured to the carrier part 26 by bolts 42. A plate shown at- 43 may be anchored to this end piece 4|, as by headed bolts shown at 44, and this plate 43 is adapted to be mounted on a lathe or other machine tool.

As shown clearly in Figure 2, the threads l2 are interrupted to provide a key-way 46, and received in this key-way 45 is a lug 46 that is carried by the flange 28. The reception of the lug 46 in the key-way 45 serves to hold the sleeve against rotation.

The mode of usage of the above specified work holder may be described by noting that when the work is first to be positioned against the face plate F the magnet assembly M will assume the retracted position shown in Figure 1. Under this condition there is some slight magnetic force evidenced at the surfaces of the pieces 2|, but this force may be readily overcome, and under this condition work may be accurately trued on the face plate F. A wrench is then inserted in any one of the sockets 36 which may be convenient, and upon the turning thereof the pinion 34 is rotated to turn the flange 32 and screw sleeve 23.

As the threads 3| carried by the latter are in mesh with the threads l2, and because of the engagement of the key 46 in the key-way 46, which holds the sleeve against rotation, the interengagement of the threads 3| and i2 moves the magnetic assembly M outwardly until the ends 23 of the magnets I engage the underfaces of the pieces 2| in the face plate F. The full effect of the permanent magnets I0 is now evidenced on the work and the latter is firmly held against the face plate F for the operations which may be performed thereon.

When these operations are completed it is, of course, desirable to remove the work from the work holder. With the strong magnetic force evidenced by the close juxtaposition of the magnet assembly M to the face plate F considerable difiiculty would be experienced upon removing the work. However, upon again inserting a wrench in tone of the sockets 36, and turning the latter, principles of mechanical advantage are brought into play so that the magnet assembly M is readily retracted from the face plate F, and when the flange 28 is abutted this magnetic force is so minimized as to render the removal of the work an easy proposition.

It is to be understood that the invention is not to be limited to any particular number or size of magnets, nor to the particular type of gear mechanism illustrated, as various modifications of these and other details might be carried out in putting the invention into practice within the purview of the appended claims.

I claim: 1 1. A work holder of the character describe comprising a magnet assembly including a plurality of permanent magnets of the horseshoe type, the ends of said magnets lying substantially in the face of said magnet assembly, a face plate including pieces of magnetic material with pieces of non-magnetic material interposed therebe-.

one end, a magnet assembly of cylindrical formation slidably received in said bore, a plurality of magnets included in said magnet assembly, a shank extending from said magnet assembly, screw threads on said shank, a screw sleeve having threads in engagement with said threads on the shank, and mechanism for causing rotation of said screw sleeve to move said shank and masnet assembly.

3. A work holder of the character described comprising a cylindrical member having a bore, a face plate carried by said cylindrical member at one end, a magnet assembly of cylindrical formation slidably received in said bore, a plurality of magnets included in said magnet assembly, a shaft extending from said magnet assembly, screw threads on said shank, a screw sleeve having threads in engagement with said threads on the shank, means for holding said magnet assembly against rotation with respect to said cylindrical member, and gear mechanism for rotating said screw sleeve.

4. A work holder of the character described comprising a cylindrical member having a bore, a face plate carried by said cylindrical member at one end, a magnet assembly of cylindrical formation slidably received in said bore, a plurality of magnets included in said magnet assembly, a shank extending from said magnet assembly, screw threads on said shank, a screw sleeve having threads in engagement with said threads on the shank, an outwardly extending flange carried by said screw sleeve, a circular rack formed on a face of said outwardly extending flange, a pinion in engagement with said rack, and means for rotating said pinion.

5. A work holder of the character described comprising a cylindrical member formed with a cylindrical bore and having a face plate at one end, said face plate including pieces of magnetic material maintained in spaced relationship by being embedded in a main body portion of non-magnetic material, a magnet assembly of cylindrical formation slidably received in said bore, said magnet assembly consisting of a main body portion of non-magnetic material in which are embedded a plurality of permanent horseshoe magnets, a shank on said magnet assembly, screw threads on said shank, said screw threads being formed with a key-way, a carrier structure connected to said cylindrical member, an inwardly extending flange formed on said carrier structure, a lug on said flange received in .said key-way, a screw sleeve having threads in engagement with the said threads on the said shank, an-outwardly extending flange carried by said screw sleeve, a circular rack formed on a face of said outwardly extending flange, pinions carried by said carrier structure and engaging said rack, and means for rotating said pinions.

6. A work holder of the character described comprising a cylindrical member formed with a cylindrical bore, a face plate removably carried by said cylindrical member at one end, said face plate including a plurality of pieces of magnetic material embedded in a main body structure of non-magnetic material and maintained in spaced relation therein, a magnet assembly,

of cylindrical formation movable in said bore, a plurality of permanent magnets included in said magnet assembly and having ends in substantial alignment with the magnetic pieces in the face plate, and means for moving said magnet assembly toward and away from said face plate.

'7. A work holder of the character described comprising a magnet assembly including at least one permanent magnet, a face plate for engaging work and transmitting magnetic lines of force from said magnet assembly through said work, and mechanism for making and holding adjustments between said magnet assembly and face plate intermediate limits of movement between said magnet assembly and face plate.

8. A work holder of the character described comprising a carrier member formed with a bore. means substantially coaxial with said bore for mounting the carrier member on a machine tool, a face plate closing said bore and including pieces of magnetic material, a magnet assembly including aplurality of permanent magnets in said bore and movable therein, and mechanism for adjusting and holding in any adjusted position said magnet assembly within said bore, said mechanism being operable from the side of said carrier member.

9. A work holder of the character described comprising work piece engaging means, a piece of metal of high magnetic permeability in said work piece engaging means, a magnet assembly including a magnet constructed and arranged to generate a magnetic flux in the direction of said work piece engaging means only, and means operating centrally of said magnet assembly for adjusting the distance between said magnet assembly and said work piece engaging means.

10. A work holder of the character described comprising work piece engaging means, a plurality of pieces of metal of high magnetic permeability in said work piece engaging means, a magnet assembly including a plurality of permanent magnets having poles substantially in alignment with said pieces of metal, said magnet assembly being constructed and arranged to generate a magnetic flux in the direction of said work piece engaging means only, and means for adjusting and maintaining alignment between said magnet assemblyand said work piece engaging. means. I

11. In a work holder of the character described, a magnet assembly including a plurality of permanent magnets embedded in a main body portion of a non-magnetic material, a face plate for engaging work and transmitting magnetic lines of force from said magnet assembly through said work, a shank carried by and disposed centrally on said magnet assembly, screw threads on the exterior of said shank, and means cooperating with the screw threads for making and holding adjustments between said magnet assembly and face plate intermediate limits of movement between said magnet assembly and face plate-- JOHN J. GRODEN. 

